4.507.2 Heating and air-conditioning system design. Heating and air-conditioning systems shall be sized, designed and have their equipment selected using the following methods:
1. The heat loss and heat gain is established according to ANSI/ACCA 2 Manual J – 2004 (Residential Load Calculation), ASHRAE handbooks or other equivalent design software or methods.
2. Duct systems are sized according to ANSI/ACCA 1 Manual D – 2009 (Residential Duct Systems), ASHRAE handbooks or other equivalent design software or methods.
3. Select heating and cooling equipment according to ANSI/ACCA 3 Manual S – 2004 (Residential Equipment Selection) or other equivalent design software or methods.
Exception: Use of alternate design temperatures necessary to ensure the systems function are acceptable.
COMMENTARY
Purpose:
Section 405.7.2 requires HVAC systems to be appropriately sized to the heating and cooling loads (heat gain/heat loss) of the structure. This section also provides an exception to allow use of appropriate design temperatures reflecting design needs of buildings instead of broad-based climate information.
Examples of Acceptable Methods of Implementation and/or Compliance:
Heat loss and heat gain calculation using software (available on the Internet) or hand calculations or an equivalent.
Duct system design to ensure adequate air flow is provided to address the heat loss and gain in each area of the home.
Select equipment which will provide the necessary air flow and level of conditioning to satisfy the loads, function within the duct design criteria and within the equipment limitations.
The referenced ACCA manuals are available from: Air Conditioning Contractors of America., 2800 Shirlington Road, Suite 300, Arlington, VA 22206 www.acca.org
Use of design temperatures consistent with the California Energy Commission’s Reference Appendices for the 2008 Building Energy Efficiency Standards for Residential and Nonresidential Buildings or a successor document.
Background:
The Air Conditioning Contractors of America’s (ACCA) technical manuals include procedures and calculations used by designers, installers and technicians with the objective of creating heating, ventilation, air conditioning and refrigeration systems that meet code requirements and ensure customer comfort.
ANSI/ACCA2 ManualJ, Residential Load Calculation: Produces equipment sizing loads for single-family-detached homes, small multi-unit structures, condominiums, town houses and manufactured homes.
ANSI/ACCA1 ManualD, Residential Duct Systems: This is a comprehensive guide outlining the methods and procedures used to design residential duct systems.
ANSI/ACCA 3 Manual S, Residential Equipment Selection: Shows how to select and size heating and cooling equipment to meet Manual J loads based on local climate and ambient conditions at the building site.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) handbooks consist of a series of four volumes titled HVAC Applications, Refrigeration, Fundamentals, and HVAC Systems and Equipment. The handbooks are available from the ASHRAE Bookstore at www.techstreet.com.
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